Improvement in expansion rock-drills



J. A. ALBRIGHT. Expansion Rook-Drills.

Patented Nov. 13, 1877.

AITORNEYS.

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UNITED STATES Parana @rrren JAMES A. ALBRIGHT, OF FAYETTEVILLE, TENNESSEE, ASSIGNOB OF ONE-HALF HIS RIGHT TO JAS. H. HOLMAN, OF SAME PLACE.

IMPROVEMENT IN EXPANSION ROCK-DRILLS.

Specification forming part of Letters Patent No. 197,075, dated November 13, 1877; application filed September 6, 1877.

lb all whom it may concern:

Be it known that I, JAM-Es A. ALBRIGHT, f Fayetteville, in the county of Lincoln and itate of Tennessee, have invented a new and mproved Rock-Drill; and I do hereby dealare that the following is a full, clear, and =xact description of the same, reference being ad to the accompanying drawing, forming )art of this specification, in which- Figured is a side view of the drill, looking hi the edge of the blades; Fig. 2, a side view f the drill, looking at the side of the blades, md with the blades projected outwardly; Fig. a view, partly in section, with the portion 3 removed.

llz'l'y invention relates to an improved rocklrill, designed to be used after the ordinary lrill, for the purpose of enL rging the hole at he bottom to form a larger chamber for conainin g the blasting material.

The improvement consists in cutting-blades rranged in guides in the drill-stock, in coniection with a spring-seated end piece, so as o be projected laterally from the stock of he drill by the impact upon the end piece, nd be again withdrawn into the drill-stock y the action of the spring when the drill is lrawn back, as hereinafter fully described.

In the drawings, A represents the drilltock of my improved rock-drill, which stock 5 made of iron, and may be either made of he same length as the ordinary drill, or be nade shorter, and provided with a screwhreaded connection, to adapt it to be screwed nto the end of the ordinary drill.

The outer end of the drill-stock is divided entrally, and the portion B made removable nd attached by screws, as shown. The cener of the drill, at this end, is also bored out, 1nd in the groove or cavity is arranged a spial. spring, (J, and the stem 1), which latter is i gidly attached to the end piece E at a point eyond the end of the drill-stock. This end iece is composed of two semi-cylindrical parts, vhich are riveted to each other, and fastened o the stem D by a single screw, a.

F are the cutting-blades, which are made of he best steel, with sharp edges, parallel with he axis of the drill-stock. These blades, at pposite ends, are inclined or beveled in opposite directions, giving to the same a dove tail shape, and are arranged with their inner ends between the drill-stock and the removable portion B, and with their outer ends between the two parts of the end piece E. Both the drill-stock and end piece are cut away upon their inner faces, with inclined edges 1) b b 1), corresponding to the beveled ends of the blades, and have, also, grooves 000 0, arranged parallel with said inclined edges. The blades have their back edges seated in lon tudinal recesses in the stem 1), and are provided with pins (Z d d d, which extend into the grooves c 0.

Now, in operating the drill, as the end piece E strikes the bottom of the previously-drilled hole, the impact forces the same toward the drill-stock. This movement, it will be seen,

causes the stem 1) to compress the spiral spring, and the grooves and edges 1) and c of the end piece, in approaching the grooves and edges 1) and c of the drill-stock, cause the beveled blades to be projected outwardly from the center with great force to produce a lateral cut and enlarge the chamber for the blasting material, the spiral spring serving to force the end piece E outwardly again and restore the blades to their position near the stem, so as to permit the drill to be drawn back without obstruction, either for removal or a second blow.

Having thus described my invention, what I claim as new is l. The combination, with a drill-stock and a spring-seated end piece, E, having stem l), of the beveled cutting-blades, arranged in guides to be projected laterally by the impact of the end piece, substantially as described, and for the purpose set forth.

2. The combination of the centrally-bored drill-stock A, having removable part 13, the spring 0, the centrally-divided end piece E, with rigid stem 1), and the beveled cuttingblades F, having pins (1 d, substantially as described, and for the purpose set forth.

JAMES A. ALBRIGHT.

Witnesses:

\V. A. GILL, Jr., G-no. J. STONEBRAKE. 

